Clarification of black foundry waste waters



March 12, 1957 R. B. BOOTH ET AL L 2,784,468

CLARIFICATION OF BLACK FOUNDRY WASTE WATERS Filed March 1l, 1952 2 Sheets-Sheet l f2 E" MAK@ ATTORNEY March 12, 1957 R. B. BOOTH ETAL 2,784,468

CLARIFICATION O BLACK FOUNDRY WASTE WATERS Filed March l1, 1952 2 Sheets-Sheet 2 CLARIFICATION F BLACK FOUNDRY WASTE WATERS Robert B. Booth and John M. Dobson, Stamford, Conn., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine Application March 11, 1952, Serial No. 275,994

11 Claims. (Cl. v22-217) This invention relates to the clarification of foundry waste efuents.

A serious waste disposal problem in foundry practice arises in disposing of the inky-black waters originating from vfoundry dust collectors, wet methods and such various operations as cleaning of foundry sands, sand blasting and hydraulic cleaning `of castings, etc. We have now discovered a means of continuously removing the contaminants from such foundry waters as a low bulk concentrate and if desired, recirculating the clarified water that has been freed of impurities; thus, our invention largely eliminates waste disposal and stream pollution problems that have plagued the industry heretofore and effects a great economy in the expenditure of water.

American steel foundry practice in the manufacture of green sand castings consists of milling or mulling bentonite or clay with a farinaceous binder, such as corn our, in a mill, and mixing it with water and sand to obtain the consistency necessary for moldability. This sand becomes facing sand and is placed next to the pattern. After removal of the pattern, the metal in the `casting comes in contact with this facing sand and reproduces the design of the pattern or model. This practice is used on castings from one to live thousand pounds each in weight, Vbut iS generally conceded to be unsuitable for castings in excess of this weight, which are usually made `in oven driedu United States Patent G long enough to till the mold cavity for very heavy castings.,

After the castings have been shaken out of the sand, the

entire contents of the flask -ormolding box may go through a sand reclamation system designed to remove steel or metal particles with a magnetic separator. The sand then.

goes through a series of screens, removing many of the fines, in order to maintain suitable permeability for the elimination of gasses in pouring.

The reclaimed product is then called heap sand or backing sand, and is used to back up the all new sand facing next to the pattern. The heap or backing sand, is not suitable for reuse as a facing sand, because it has become contaminated with various ingredients which have become burnt and inert, such as clay and corn flour. In addition, certain molds are coated with linseed oil or its equivalent. This oil coating having been burned onto the sand, is very difficult to remove by washing, scrubbing or ignition.

Heap sands may be cleaned by scrubbing or washing, followed by screening, classification, settling, etc. Such cleaning processes produce the above-mentioned black foundry waters. Th'ese'waters contain burned sand particles, that is, carbon-coated silica, as well as other constituents of the mixtures used for the molds, for example, clay, bentonite, carbon, graphite, thermosetting resins, high organic polymers, and thermal degradation products of the organic binders used, in a highly colloidal form. Clarification by settling and/ or filtration is extremely ditiicult and is not commonly used because of the ineiiiciency of such methods. Reagents which are known to be effective in promoting the'otation of carbon and graphite, for

2,784,468 Patented Mar. 12, 1957 RCC example, fuel oil in combination with frothers, surprisingly enough, do not promote the otation of this `colloidal black matter.

In recent years American foundries have adopted sand blasting to cleanv both the casting itself and Vto scrub off the pyrolized ycoatings from the foundry sand. Dry sand blasting is sometimes used,the sand entrained by the out-going air being trapped inwater to give suspensions which must be claricd before disposal. Wet sand blasting is highly effective; a mixture of sand and water under high pressure (e. g., up to 1800 lb./`sq.inch)is directed against the casting to remove any adhering sand, decomposition products, oxidation products, etc., from the casting and simultaneouslyzto clean -the sand itself. The cleaned sand is recovered for reuse and the water after the separation -is heavily loaded with the abovedescribed solids. A portion of these solids may b e removed by settling, but large quantities of the solids', particularly the fines and colloidal fractions, remain in suspension and create a serious disposal problem.

High pressure water alone may be used for the cleaning of castings. As described above, high pressure streams or sprays of Water are directed against the casting to dislodge and remove adhering sand, scale, decomposition products, etc. This operation also produces dark-colored `suspensions which are extremely diilicult to filter and clarify and which create the same problems in reuse and Vdisposal as indicated above.

It is, therefore, an object lof the present invention ,to provideV both an apparatus for, and a method adaptedtto, carry out the foundry sand cleaning operation and at the same time to remove carbonaceous impurities from the foundry waste water Iin an eflicient but simple manner.

lDarlecolored suspensions also result when wet dust collectors are used in foundry practice; such suspensions present the same disposal problem as described above.

It is an advantage of our new process that the suspended solids are removed from these contaminated waters to produce a clarified effluent containing less than 500 p. p. m. solids. In this manner, we have eliminated most `of the undue wear of the high pressure circulating pumps that normally handle contaminated foundry waters. Thus, if desired, it is now possible to use a locked system in VAwhich-the clarified waters are recirculated and the contaminants are continuously removed as a low bulk ota- A tion concentrate. On the other hand, the clarified waters are sumciently free of solids to allow their disposal in streams without presenting a serious pollution problem.

In our new process .these foundry waste waters are clarified by flotation with anio'nicl collectors, either in the presence or absence of glue and related substances, Yor the waters may be first settled with or without settling agents in combination with the flotation step mentionediabove. The choice of the method used depends on the type of waste water to be treated and ourl invention will be illus- Vtrated in conjunction with the accompanying drawings in which Figure 1 is a flow sheet of a continuous method of recovering sand sufficiently clean for reuse and water 'suitable for circulating. Figure 2 illustrates an adaptation of our process which permits the clarified water to be reused inthe wet type dust collector. Figure 3 is a flow sheet of aY continuous process for-cleaning castings by Wet sand Y closedliereinbut is to.be accorded the 'full scope ofthe vclaims-.so as toembrace any .and all equivalent devices. .'Having ,described ourinvention, what we claim as new and desire to secure by LettersPatent is:

A'1. A mechanical action' for artificialk limb joints comprising airelatively stationary member and a ratchet segment rotatably mounted on the member, alever rota- .tabl-y mounted on the member with the ,rotational axis .adjacent to'the circumference of the ratchet segment, a locking bar on said leverhaving opposite curved faces positioned generally perpendicular to the radius from the rotational axis of the lever, said segment having a iseries of spaced generally radiallyextending bar receiving notches lwith faces complementary to the respective 'faces ofthe barwhen inbar receiving position, said rotational axis'of the lever beingat a point adjacent a iine "tangent to'an arc'about the-axis of said segment struck through the centers of the faces-of said notch.

Y2. lA mechanical action for artificial limb joints com- `prising va relatively stationary Vmember and a ratchet segment-rotatably mounted on themember on the axis of rotation of the joint, a lever rotatably mounted on the 'member with the rotational axis ladjacent to and exterior ofthe circumference of the ratchet segment, a locking lbaron said lever havingopposite faces positioned generallyV perpendicular to the radius from the rotational axis `of the lever and vthe faces, saidsegment being subject to :a -rotative load and having a series of spaced generally -radially extending bar receiving notches with faces corn- `plementary to the respective faces of the bar when in fbarrreceiving position, said-rotational axis ofthe lever .being ywithinan angular distanceof a line tangent to an 'rarclabout the axisrof said segment struck through the .centers of the faces of said notch such that the component rofthe forceA resulting from. application of a rotative load Vtendingto disengage the bar from the notch is less than ,the'frictional force on the respective contacting faces.

3. A mechanical action for artificial limb joints comprising a relatively stationary member and .a ratchet :segment rotatably mounted on the member on the axis of rotation of the joint, -a lever rotatably mounted on the member with the rotational axis adjacent to and exterior of the circumference of the ratchet segment, a locking bar on said lever having opposite arcuatefaces positioned generally,perpendicular to the radius from the rotational -axis of the lever and the faces, said segment having a series of spaced generally radially extending bar receiv- Ving notches with arcuate faces complementary to the `respective faces of the bar when at bar receiving position, said rotational axis of the lever being within an angular distance of live degrecsinside of a line tangent to an arc about the axis of said segment struck through the centers of the faces of said notch.

4. A mechanical action for artificial limb joints comprising a relatively stationary member and a ratchet segment rotatably mounted on the member on the axis of rotation of the joint, a lever rotatably mounted on the member with the rotational axis adjacent to and exterior of the circumference of the ratchet segment, a locking bar on said lever having opposite arcuate faces of radius of curvature determined by the distance between the rotational axis of the leverand the respective face, said segment having a series of spaced generally radially extending 'bar receiving notches Vwith earcuatevffaces comple-I mentarytotherespective faces ofthe bar, ,said rotational axis ,of `theflever vbeing at a jpoint iwithin Lan angular distance of l5 degrees 'oneither side "of 'a yliney tangent `to an arc centered attheeaxis of said segmentand through thecenters Vof'thcfaces of a notch inibar ,engaging -position, 'the vfaces Yof said `notches having positions -wherein said lastfaces are in engagement substantially throughout their areas'with therespective faces o f-thebar when in bar'engaging position.y

5. A mechanical action for; artificial limbjoints comprising apair of members wherein one member` is adapted for attachment to a Vnatural limb,-paralleljplates on one of the members, the other ofsaid members comprising a tubular sleeve rotatably mountedfon-'said Vplates providing thereby an articulating joint for `said action, aratchet'segment tixedon-said sleeve -having a series ofspacedegenerally radially extending notches, a'lever pivotally mounted at acenter of rotation on'said one member, a locking bar fixed transversely on the lever, and an alternator connected between theleverand ,one of said ,members adapted to releasably hold said'bar yout'of lnotch engagementrposition, said Abar having opposite notch contacting facescurved in the same general direction and saidtnotches having opposite curved bar engaging faces complementary to and adapted to engage Ythe respective faces of :the bar when in bar engaginggposition.

6. A mechanical action for artificial limb joints cornprising a relativelystationary member adapted for attachment lto a natural limb, parallel plates on said member anda `tubular vsleeve rotatably mounted on said plates providing thereby an articulating joint for said action, a ratchet 'segment fixed on said sleeve having a series of spaced generally radially extending notches, a lever pivotally mounted-at a'center of rotationon said member, a locking bar-fixed transversely on the lever, a spring on said member normally urging said bar toward a notch engagement position, and an alternator connected between said (member and the lever adapted to releasably hold said bar out of notch engagement position, said bar having opposite notch contacting faces of arcuate form and of radius determined by the-distance between 'the respective face and said center of rotation of the lever, said notches having opposite bar engaging faces of arcuate form complementary to and adapted to engage the respective faces of the bar when in bar engaging position.

7. A ratchet resistant mechanical action for artificial limb joints comprising a base, a ratchet segment rotatably mounted on the base Vand a locking bar having a pivotal mounting on said base, said locking bar having opposite segment-engaging faces curved in the same general direction about the axis of said pivotal mounting, said segment having a series of peripheral bar receiving notches with opposite faces respectively complementary to the faces on said bar.

References Cited in the le of this patent 'UNITED STATES PATENTS Germany Feb. 11, 1918 EXAMPLE 5 Table 1V Run A Run B 0.61? lb.,l1,000 gals. lime as milk oi 0.21b./1,000 gais. dry lime.

e. 0.11 lb./I,000 gals. ul-ack liquor p. 0.07 lb./1,000 gals. pine oil No pine oil used. 94.6% removal of suspended solids..

91.3% removal of suspended solids.

EXAMPLE 6 Samples of black-colored waters from a Pennsylvania cast iron foundry were treated by flotation. The waters, containing 4230 p. p. m. suspended solids, were passed continuously to a settling tank, treated with 0.23 lb./1000 gallons of lime and allowed to settle seven minutes. The waters were then passed to a Fagergren flotation machine, treated with 0.44 lb./1000 gallons black liquor soap and 0.05 lb./1000 gallons bone glue, and iloated for four minutes. An eiluent containing 390 p. p. m. suspended solids was produced.

A second sample of sand blast waters from this foundry was also treated. From a water containing 2720 p. p. rn. suspended solids, an effluent containing 230 p. p. m. was produced by the above-outlined procedure, employing per 1000 gallons 0.7 lb. hydrated lime, 0.44 lb. black liquor soap, and 0.05 lb. bone glue. The flotation concentrateV was. black in color when wet and gray-to-black on diying at 110 C. The dried solids were ignited at about l000 C.- to remove volatile constituents; the resulting residue, 71.2% of the sample, was light yellow in color and was 'composed mainly of silica with some silicate minerals and iron oxides also present.

EXAMPLE 7 i A foundry sand contaminated by use in steel casting was scrubbed and washed with water. The sand, after this cleaning operation, was recovered by classication and settling and the resulting wash waters were reserved for flotation testing. These waters, black in color, were typical of the eluents produced in foundry sand reclamation and contained 3050 p. p. m. suspended solids.

The coarser portions of these contaminants settled out on standing, but the liner portions remained in suspension for several days; in fact, at the end of seven vdays the supernatant liquid was still highly colored with suspended colloidal material.

In conducting tests on these waters, representative portions were settled for two and one-half minutes with a settling agent to remove a portionof the suspended solids and the supernatant liquid, still contaminated with suspended matter, was passed to a Fagergren dotation machine, treated with otation reagents, and oated for one and one-half minutes.` The suspended solids, thus con ceutrated in the froth, were skimmed od.

' Since the waters were contaminated with carbonaceous materials, charred and carbon-coated sand grains and inineral matter, etc., an attempt was made to clarify the waters by settling, followed by dotation reagents usually employed for floating carbon, graphitic material, etc., in regular dotation practice.

The waters were iii'st settled with 0.54 lb./ 1000 gallons alum for tive minutes and the supernatant liquid floated for one and one-half minutes with 0.15 lb./ 1000 gallons of a higher alcohol frother. No promotion of .thel suspended solids was obtained. Similarly, a combination of 0.22 lb./1,000 gais. black liquor soup. i

0.15 lb./1000 gallons alcohol frother and.: 0.15 lim/ 1000 tgallons fuel oil #2 did not promote thefiotation ofthe suspended solids. Pine oil, 0.05 lb./l000gga1lons, gave good froth, but did not promote the flotation of vthe suspended solids. Thus, reagentsl commonly used in flotation or' carbon, graphite, etc., were not effective for removing the carbon-contaminated solids from these waters. Black liquor soap, 0.44 lb.,/10,00 gallons, gave an eluent containing 700 p. p. in. suspended solids, a considerable improvementover the above-listed results. Glue, 0.07 lb./ 1000 gallons, produced some froth, but very little collection of the suspended solids; a lcombination of 0.7 lb./1000 gallons glue and 0.07 lb./1000-pine oil also gave poor promotion of the suspended solids, resulting in an etliuent -containingabout 2,500 p. p..m. suspended solids. However, a marked improvement in clarity was obtained using 0.10 lb./-1000 gallons black liquor soap in combination withl 0.036 l.lb./1000 glue; the froth and promotion of solids was improved markedly `and the resulting euent contained 625 p. p. rn. suspendedsolids, considerably less than obtained in any of the tests described above.

In View of the improved results obtained with the glueblack liquor soap-combination, a number ofv settlingotation tests were conducted, employing a variety of glues and related 4materials, and several anionic type flotation collectors. The above-described waters were settled three minutes with various settling agents, as described above, and then floated one and one-half minutes with various glues and related products used in combination with a variety of anionic type notation promoters. The glue and promoterswere added in two `equal stages, the first at the start, followed by a 15.second condition'- ing period, and theV second after ione-half minute of flotation. The following table summarizes the `results obtained 1n these tests.

Table V Settling (3.0 Fiotation (1.5 Min.) Pro Eflluent, Min.) Agent meter Used, 0.44 lb./l,000 Glue Typel p. p.fm. and ib./1,000 gallons (0.07 ltr/1,000 gal.) Suspended gal. Solids Alum, 0.54..-. Black liquor soap kk60 Do.` d 6l Do.- do 101 Do d Do.. do. 62 Do Sodium naphthenate. 420 Do do 53 Do. -do.. l62 Do do 60 8l 83 Vl72 97 79 438 250 Sulfonated voleic acid. Sa-poniied talloel Ammoniated talloel Sodium oleate Seponifiod rosin- (gum) Saponiflod rosin (wood).- Sulfonated rosin Black liquor soap..

Do .do Lime, 0.72.... do Hid Ferrous Suldo tate, 0.90. Y

l Figures in parentheses are jellygrams.

After settling vwith 0.54 lb./ 1000 gallons alum, {0.07 lb./ 1000 gallons of gelatine (acid andbasic types) were used in separate tests with 0.44 lb./1000 gallons black liquor soap; eilluents containing 1,10and 126 p. p. m., respectively, were produced. -After a similar vsettling treatment, two ammoniated caseins were used in amounts of 0.07 lb./.1000 gallons in combination with 0.44 1b.! 1000vgalions black liquor soap; the resulting .eilluents contained 350-400 p. p. in. suspendedsolids. Y

In another series oftests on this'water,.-0.25 lla/1000 dotation in the presence of black liquor soap and in the absence 'of an added reagent capable of activating silica, to produce a flotation concentrate rich in said impurities and a water tailing substantially free thereof; and recycling at least a portion yof said tailing for reuse.

6. In a method of foundry operation which comprises casting metal in :a sand mold, whereby Vthe organic binder present in said mold is pyrolized and carbonized; freeing the carbonized organic matter, finely divided silica and other impurities from said sand by a hydraulic process, whereby a suspension of said impurities in water is obtained; Ithe steps which comprise settling said Water suspension; subjecting the settled water suspension to froth otation in the presence `of saponiiied talloel and in the absence of an added reagent capable Iof activating silica, to produce a dotation concentrate rich in said impurities and a water tailing substantially free thereof; and recycling at least 1a portion of said tailing for reuse.

7. In a method Vof foundry operation which comprises casting metal in a sand mold, whereby the organic binder present in said mold is pyrolized and carbonized; freeing the carbonized organic matter, finely divided silica and other impurities from said sand `by -a hydraulic process, whereby a suspension of said impurities in water is obtained; the steps which comprise settling said water suspension; subjecting the settled Water suspension to froth otation in the presence of talloel and a small amount of glue and in the absence of an added reagent capable of activating silica, to produce a dotation concentrate rich in said impurities and a water tailing substantially free thereof; and recycling at least a portion of said tailing for reuse.

8. In a method of foundry operation which comprises Y casting metal in a sand mold, whereby the `organic binder present in said mold is pyrolized and carbonized; freeing the carbonzed `organic matter, finely divided silica and vother impurities from said sand by a hydraulic process; the steps which comprise settling vsaid water suspension; subjecting the settled Water suspension to froth flotation in the presence of black liquor soap land a small amount of glue and in the absence of an added reagent capable of activating silica, to produce a flotation concentrate rich in said impurities and a water tailing substantially free thereof; and recycling at least a portion of said tailing for reuse.

9. In a method of foundry operation which comprises casting metal in a sand mold, whereby the organic binder present in said mold is pyrolized and carbonized; freeing the carbonized organic matter, finely -divided silica and -other impurities from said sand by a hydraulic process, whereby a suspension of said impurities in water is obtained; the steps which comprise settling said water suspension; subjecting the settled water suspension to froth flotation in the presence of saponied talloel and a small amount of glue and in the absence of an added reagent capable of activating silica, to produce a flotation concentrate rich in said impurities and a water tailing substanrtially free thereof; and recycling at least a portion of `said tailing for reuse.

l0. A method according to claim 1 in which the settling step is carried out in the presence of alum.

11. A method laccording to claim 1 in which the settling step is carried out in the presence of lime.

References Cited in the le of this patent UNITED STATES PATENTS 1,388,868 Jones et al. Aug. 30, 1921 1,861,428 Furnas May 31, 1932 2,222,728 Tartaron Nov. 26, 1940 2,259,420 Hills Oct. 14, 1941 2,261,947 Barnebl et al. Nov. 11, 1941 2,383,045 Den Breejen et al Aug. 21, 1945 2,416,909 Crawford et al. Mar. 4, 1947 2,420,392 Christensen etal. May 13, 1947 2,424,552 Clemmer et al July 29, 1 947 2,466,671 Gieseke Apr. 12, 1949 2,480,748 Luce et al. Aug. 30, 1949 2,553,905 Evans May 22, 1951 2,607,199 Christensen Aug. 19, 1952 2,607,486 Barr Aug. 19, 1952 OTHER REFERENCES Handbook of Mineral Dressing (C) 1945, sect. 12, pages 12 and 13; sect. 15, pages 06, 08 and 09.

Colliery Engineering, September 1950, pages 373 and 374.

Chem. and Metallurgical Eng., vol. 26, No. 11, pages SOO-503. 

1. IN A METHOD OF FOUNDRY OPERATION WHICH COMPRISES CASTING METAL IN A SAND MOLD, WHEREBY THE ORGANIC BINDER PRESENT IN SAID MOLD IS PYROLIZED AND CARBONIZED; FREEING THE CARBONIZED ORGANIC MATTER, FINELY HYDRAULIC PROCESS, OTHER IMPURITIES FROM SAID IMPURITIES IN WATER IS OBWHEREBY A SUSPENSION OF SAID IMPURITIES IN WATER IS OBTAINED; THE STEPS WHICH COMPRISE SETTLING SAID WATER SUSPENSION; AND SUBJECTING THE SETTLED WATER SUSPENSION TO FORTH FLOTATION IN THE PRESENCE OF A WATER-DISPERSIBLE ANIONIC PROMOTER HAVING THE FORMULA RX IN WHICH R IS A CARBOXYLIC ACID RADICAL THE MOLECULAR WEIGHT OF WHICH IS GREATER THAN 172, AND X IS HYDROGEN OR AN ALKALI METAL, AND IN THE ABSENCE OF AN ADDED REAGENT CAPABLE OF ACTIVATING SILICA, TO PRODUCE A FLOTATION CONCENTRATION RICH IN SAID IMPURITIES AND A WATER TAILING SUBSTANTIALLY FREE THEREOF. 